In the past, there has been proposed, as a faucet installed in a kitchen, a bathroom, a restroom, or the like, an automatic faucet for determining whether to start or end water discharging according to a detection result of a detection object in a vicinity of a water outlet (e.g., see JP 5212908 B2). A detector for detecting the detection object may include a Doppler sensor for sending and receiving radio wave signals, and is to detect motion of the detection object based on comparison between an output of the Doppler sensor filtered with a filter and a threshold value.
In short, the detector of the conventional faucet recognizes the detection object based on intensities of signals in a particular band of time axis information.
However, the faucet including a conventional detector using radio waves is likely to cause miss detection and false detection. The miss detection means failing to detect the detection object when the detection object is in fact present. The false detection means determining that the detection object is present when the detection object is in fact not present.
For example, even if the detection object is in fact not present, the detector may receive a reflected wave reflected by a water flow discharged from the water outlet, and thereby erroneously recognizes that the detection object is present. This may occur frequently in a case where the water outlet discharges a relatively high pressure water shower.
When the detector includes a photosensor using infrared or the like, it has difficulty in detecting black or transparent objects. Additionally, the false detection may be caused by sunlight.
Hence, there may be a demand to realize a faucet which is unsusceptible to unwanted effects such as effects of a surrounding environment, and a color and a material of an object, and thus can accurately determine whether a detection object is present in a vicinity of a water outlet, irrespective of a water volume and a condition of a water flow (e.g., a shower and a stream).